JP2001345205A - Method of forming thin-film resistor element in printed board, thin-film resistor element and thin-film capacitor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of forming a thin-film resistor in a printed board in which the thin-film resistor, in which size and thickness are controlled with high accuracy, can be formed. SOLUTION: The method of forming the thin-film resistor element 10 in the printed board 12 has a thin-film resistance-layer forming process, in which a thin-film resistance layer 26 having fixed thickness is formed by a dry process used for a semiconductor process or the like on an insulating layer 14 on the printed board, a conductive-layer forming process, in which a conductive layer 28 is formed onto the thin-film resistance layer, and a thin-film resistor forming process, in which the thin-film resistor 16 having a fixed resistance value is formed between at least two conductive-layer pads 18 by forming the conductive- layer pads by selectively etching the conductive layer. Accordingly, the thin-film resistor, in which size and thickness are controlled with high accuracy, can be formed. The upper and lower electrode layers are formed by interposing a dielectric layer on the inside by using the same technique, and a thin-film capacitor can also be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thin film resistor on a printed circuit board, a thin film resistor, and a thin film capacitor.

[0002]

2. Description of the Related Art In general, printed circuit boards used in various electronic devices and the like are required to be further reduced in size and weight. Among them, how to incorporate a resistor maintains the accuracy of the resistance value. Together with the demand for miniaturization
It is important. As an example of a method of forming such a resistor, for example, when a ceramic substrate is used,
It is common practice to apply a resistive paste on the wiring on the surface of the ceramic substrate by a printing method to form a resistor. A resistor formed by this printing method is called a print resistor.

A method for manufacturing such a printed resistor will be described with reference to FIG. In FIG. 20, reference numeral 2 denotes a ceramic substrate, the surface of which is an insulating layer (insulated state). First, Ag-Pd is placed on the ceramic substrate 2.
A conductive paste made of a paste or the like is applied by a printing method to form conductive layer pads 4 separated by a predetermined distance (FIG. 20A). Next, a printed resistor 6 is formed by applying a resistive paste by a printing method so as to connect the separated conductive layer pads 4.

[0004]

By the way, the resistance value of the printed resistor 6 is determined by the applied size of the resistor paste, that is, the resistance length L, the resistance width W (not shown), and the film thickness t.
Depends on. As described above, since the resistance value changes depending on the size of the printed resistor 6, the following problem occurs. First, when screen printing is performed on the conductive paste or the resistive paste, it is difficult to avoid the occurrence of bleeding, printing deviation, and the like, and there has been a problem that the resistance value of the printed resistor 6 varies. In particular, the thickness of the resistor paste varies greatly because printing conditions such as squeegee pressure and squeegee angle, and the viscosity of the resistor paste are difficult to control. As a result, the variation in the resistance value of the printed resistor 6 further increases. There was also a problem that it would be encouraged.

When the conductive layer pad 4 is made of copper, ohmic contact with the conductive layer pad 4 is difficult to make, and the contact portion of the conductive layer pad 4 has an extra resistance. There is also a problem that it is difficult to obtain a resistance value as designed. For this reason, the resistance value generally has a large variation of about ± 30% with respect to the set value. Therefore, there is a disadvantage that the resistance value needs to be adjusted by trimming or the like in the final stage. In addition, the demand for miniaturization and thinning as described above has been placed not only on resistors but also on capacitor elements. As a capacitor element corresponding to this request, for example, a capacitor element disclosed in Japanese Patent Application Laid-Open No. Hei 9-116247 is known. In this case, a capacitor is formed by providing an opening in an insulating layer, filling a dielectric paste in the opening, and sandwiching the paste between upper and lower electrodes. However, since the thickness of the insulating layer is usually several tens μm or more, the thickness of the dielectric is large, which is disadvantageous for high capacity. The present invention has been made in view of the above problems, and has been made in order to effectively solve the problems. The purpose of the present invention is to form a thin film resistor whose dimensions and thickness are controlled with high precision. It is an object of the present invention to provide a method of forming a thin film resistor on a printed circuit board, a thin film resistor, and a thin film capacitor element.

[0006]

According to a first aspect of the present invention, in a method of forming a thin film resistor element on a printed circuit board, a dry process used for a semiconductor process or the like is formed on an insulating layer on the printed circuit board. Forming a thin-film resistance layer having a predetermined thickness; forming a conductive layer on the thin-film resistance layer; and selectively etching the conductive layer to form at least two conductive layers. Forming a thin film resistor having a predetermined resistance value between the conductive layer pads by forming layer pads. As a result, a thin-film resistance layer with high film thickness accuracy can be formed, and since the conductive layer pads are formed by the photolithography method, the planar dimensional accuracy can be increased. As a result, the resistance value of the thin-film resistor can be improved. Variations can be suppressed and controlled with high accuracy.

In this case, as defined in claim 2, the thin-film resistor is used for forming a build-up substrate or a build-up multilayer substrate in which an insulating layer and a patterned conductive layer are sequentially laminated on a core material. It may be made.
According to a third aspect of the present invention, there is provided a thin film resistor manufactured by the method according to the first aspect of the present invention. That is, in a thin film resistor element on a printed board, the thin film resistor is provided on an insulating layer on the printed board. A thin-film resistance layer having a predetermined thickness formed by a dry process used in a semiconductor process or the like; and at least two conductive layer pads formed separately on the thin-film resistance layer to form the thin-film resistor And In this case, as described in claim 4, when the thin film resistor is a thin film resistor provided in an inner layer, the thin film resistor may be provided on an insulating layer above the thin film resistor or on a conductive layer near the thin film resistor. May be formed with a concave portion for heat radiation. According to this, it is possible to enhance the heat dissipation of the heat generated from the thin film resistor. Claim 5
According to the invention according to the present invention, in the thin film capacitor element on the printed board, the lower electrode layer having a predetermined thickness formed by a dry process used in a semiconductor process or the like on the insulating layer on the printed board; A dielectric layer formed on the layer by the dry process; and an upper electrode layer formed on the dielectric layer by the dry process, wherein the lower electrode layer extends more horizontally than the upper electrode layer. A thin-film capacitor element on a printed circuit board, which is connected to a lower electrode lead-out pad. As a result, a thin film, upper and lower electrode layers and a dielectric layer having high planar dimensional accuracy can be formed, and as a result, it is possible to suppress variations in capacitance values and control them with high accuracy. In this case, the upper surface of the upper electrode layer and the upper surface of the lower electrode lead-out pad are substantially at the same height. Further, for example, as defined in claim 7, the insulating layer on the printed circuit board is provided in claim 3 or 4.
And is provided on the same surface side as the thin-film resistor element.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for forming a thin film resistor element on a printed circuit board, a thin film resistor element and a thin film capacitor element according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows a first example of a thin film resistor element according to the present invention.
FIG. 2 is a perspective view showing a second embodiment of the thin-film resistor element according to the present invention, and FIG. 3 is a cross-sectional view showing a third embodiment of the thin-film resistor element according to the present invention. . According to the present invention, a thin film resistor is formed using a method completely different from a conventional method using a screen printing method. As shown in FIG. 1A, the thin-film resistor element 10 is formed on an insulating layer 14 on the surface of a printed circuit board 12. In this case, the insulating layer 14 may be an insulating layer on the surface of the printed circuit board 12 itself, or may be an insulating layer after a build-up layer is formed over a plurality of layers on the printed circuit board 12; Any of the insulating layers can be applied. In the actual basic configuration of the printed circuit board 12, a layer pattern made of, for example, copper is formed on the core material, but the illustration of the layer pattern is omitted in the illustrated example.
In this case, the insulating layer 14 is formed above the layer pattern.

The above-mentioned thin-film resistor element 10 is made of the insulating layer 1
On the upper surface of the thin film resistor 4, a thin film resistor 16 having a predetermined thickness t in the illustrated example and patterned in a rectangular shape, for example, and a pair of conductive layer pads made of Cu, for example, formed on both ends of the thin film resistor 16 18 mainly. The resistance value of the thin-film resistor element 10 is determined by the thickness t and the pattern size of the thin-film resistor 16, specifically, the resistance width W and the resistance length L.
(The distance between the opposing surfaces of the pair of conductive layer pads 18). To form the thin film resistor 16, a dry process used in a semiconductor process or the like is used. As a film forming method by this dry process, there are a sputtering method, an ion plating method, an evaporation method, a CVD method and the like. One of the features of the film formation by the dry process is that the film thickness can be easily controlled as compared with the screen printing method used conventionally, so that the film can be formed with a predetermined film thickness with high accuracy.
In the dry process, there is photolithography as a patterning method, which also has better pattern accuracy than the screen printing method.

In order to form a pair of conductive layer pads 18, a conductive layer is formed on the entire surface, and only this conductive layer is selectively (only the conductive layer is etched leaving the thin film resistor 16 layer). In addition, by etching to a predetermined size (resistance length L × resistance width W), the lower layer of the thin-film resistor 16 is exposed to form the thin-film resistor 16, whereby an arbitrary resistance value can be set. . As described above, the thin film resistor 16 having higher accuracy than the screen printing method can be formed by the dry process. The thin film resistor 16
And the like can be formed by using an insulating layer, such as a resin, and a contact layer for obtaining adhesion between the conductive layer, which forms the conductive layer pad 18, such as Cu.

[0011] The present applicant has filed an earlier application (Japanese Patent Application No. 11-95).
No. 469), the adhesion between the conductive layer and the insulating layer is reduced by the fine patterning, and the conventional surface treatment method cannot provide sufficient adhesiveness. It has been proposed to form a contact layer by the following method. This contact layer is patterned to form a thin film resistor 16. This thin film resistor 16
, Various resistance materials such as Ni, Ni—Cr, and Ni—Cu can be applied. Thus, the thin-film resistor element 10 of the first embodiment shown in FIG.
1 shows a basic model, and a thin film resistor element 10A shown in FIG. 1B shows an embodiment in which the width W2 of the thin film resistor 16 is changed, for example. In the second embodiment shown in FIG. 2, the thin film resistor element 10 having the shape shown in FIG. 1A and the thin film resistor element 10A having the shape shown in FIG. Are connected in series. The respective resistance lengths are represented as L1 and L2.

In the third embodiment shown in FIG. 3, for example, a build-up substrate (including a build-up multilayer substrate) formed by sequentially laminating an insulating layer and a patterned conductive layer on a core material is included. ) To which the present invention is applied.
That is, a lower layer thin film resistor 16A and an upper layer thin film resistor 16B are laminated with an insulating layer 14A interposed therebetween, and both sides of the thin film resistors 16A and 16B are each made of a conductive material made of, for example, Cu. They are connected by layer pads 18B. Thereby, both the thin film resistors 16A, 16A
B is connected in parallel. Here, each thin film resistor 16
The resistance lengths of A and 16B are represented as L3 and L4, respectively.

Next, a method of manufacturing the above-described thin film resistor element will be described with reference to FIG. Here, an example in which a core material as a build-up multilayer substrate in which a copper-clad is formed on the surface of a plate-shaped core is used as a printed board will be described as an example. In FIG. 4A, reference numeral 20 denotes a core material (printed circuit board) having a surface of a core 22 made of a resin plate or the like and having a copper clad 24 formed thereon. It has become. The surface of the inner layer pattern 24A is subjected to surface treatment such as blackening or soft etching, and the insulating layer 14 is formed thereon by screen printing or the like. Then, the insulating layer 14 is subjected to a surface treatment (roughening or activating treatment) by a dry or wet process.

Next, as shown in FIG. 4B, a material (for example, Ni: 99.9%
Is formed by a dry process, for example, a sputtering method, and a thin film resistance layer 26 having a predetermined thickness, for example, about 0.15 μm is deposited. The film forming conditions at this time are, for example, gas used = Ar, gas pressure = 0.4 Pa (3 mTorr), DC
Power output = 400 W, temperature = normal temperature. At this time, the variation in the film thickness of the thin-film resistance layer 26 due to the sputtering method is ±
The accuracy of the film thickness is much better than ± 20%, which is about 5%, which is a variation in the film thickness of the resistance paste by the conventional printing method. The dimensional accuracy in pattern formation of the thin-film resistance layer 26 is about ± 5%. Next, plating conduction is established with the thin film resistance layer 26, a conductive layer 28 made of, for example, Cu is formed on the thin film resistance layer 26 by electroplating as shown in FIG. Is formed. In particular, when using a resistive material having a high resistivity, plating continuity is difficult to take.
By forming a thin-film Cu layer by sputtering or the like after the formation of the thin-film resistance layer 26, copper plating becomes possible. In this patterning, both the conductive layer 28 and the thin-film resistance layer 26 are etched. For example, in the case of the conductive layer Cu / thin film resistance layer Ni, if a cupric chloride solution is used, these can be etched simultaneously. Further, the conductive layer 28 and the thin-film resistance layer 26 may be etched separately according to design specifications, or may be etched simultaneously.

Next, as shown in FIG. 4D, as a mask material for selective etching, for example, a photo solder resist 30, which is usually used as a protective film, is applied by screen printing, and is exposed and developed. A pattern to be a thin film resistor is formed. This photo solder resist 30
Corresponds to the alkali etching solution in the next step,
It is preferable to use one having alkali resistance. Next, as shown in FIG. 4E, only the conductive layer 28 is etched using the photo solder resist 30 as a mask. Usually, the solution for etching Cu is an acid-based solution. However, in order to leave the underlying thin-film resistance layer 26, an alkaline solution is used here to provide selectivity. As the etching solution, for example, an A process solution manufactured by Meltex can be used. The etching conditions were as follows: temperature = 4.
It may be performed by a spray method at 5 ° C. and time = 60 seconds. As a result, the Cu forming the conductive layer 28 is completely etched out except for the mask portion, and the underlying thin film resistance layer 26 is exposed on the surface. Exposing the surface of the exposed thin film resistance layer to ESCA
As a result of surface analysis using (manufactured by ULVAC-PHI), there was no difference in the peak amount of Ni as compared with the surface state after sputtering. The thickness of the thin-film resistance layer 26 made of Ni was measured, and there was no difference from the value after sputtering.

Next, by removing the photo solder resist 30 serving as a mask, the remaining conductive layer 28 is exposed and formed as the conductive layer pad 18 as shown in FIG. At this time, the photo solder resist 30 was stripped using a dedicated liquid, for example, a resist stripper 9296 manufactured by MacDermid Japan. As described above, the dimensional accuracy of the size of the thin film resistor 16 can be made ± 5% by using the photolithography process or the like for the patterning shown in FIGS. 4D, 4E, and 4F. Therefore, it is possible to control the dimensions with high accuracy compared to the dimensional accuracy ± 10% of the resistance paste of the conventionally used screen printing method. Further, the resistor is not limited to the thin film resistor 16 described above, and generates heat when energized. The degree of the heat generation depends on the current density, the resistance material, the installation state, and the like.
For example, the inner-layer resistor is sandwiched by an insulating layer (resin) above and below the outer-layer resistor, so that it has poor heat radiation properties, and thus has a characteristic that the temperature rise due to heat generation becomes large. Therefore, as shown below, the thin film resistor 1
6 may be improved in heat dissipation.

First, the thin film resistor 16 having a short resistance length L5 is used.
Are arranged in series as shown in FIG. 5A, it is possible to apply a larger power than the thin film resistor 16 having a longer resistance length shown in FIG. 5B. At this time, the resistance length L
5, L6 has the relationship of the following equation. Resistance length L5 × n
(Positive integer) = resistance length L6 FIGS. 6A and 6
As shown in (B), when the thin film resistor 16 is covered with the insulating layer 32 and is formed as an inner layer, the thin film resistor 1
6 or a conductive layer (conductive layer pad 1)
8) In the upper insulating layer 32 of FIG.
For example, holes and grooves may be formed to promote heat radiation. In the illustrated example, a case where a recess 34 is formed in the insulating layer 32 above the conductive layer pad 18 is shown. In this case, as shown in FIGS. 7A and 7B, a heat conductive layer 36 made of, for example, a conductive material is provided on the inner surface of the concave portion 34 for heat radiation so as to promote heat radiation efficiency. It may be. Still further, in this case, as shown in FIG.
By forming the uneven fins 38 by a roughening process or the like and increasing the surface area thereof, the heat radiation efficiency may be further improved.

Further, the case where the thin film resistor is formed on the same plane has been described as an example, but the present invention is not limited to this. The circuit patterns on the same plane may be different from each other via via holes formed in the insulating layer, or may be different. Of course, the present invention can be applied to a case where a thin film resistor is joined between circuit patterns of layers. For example, FIG. 9 is a sectional view showing a case where a thin film resistor is formed between inner layer circuit patterns. FIG.
As shown in (A), for example, via holes 4 are formed in insulating layer 42 formed on inner layer circuit pattern 40 on the surface of core material 20.
4 is formed to expose the inner layer circuit pattern 40, and a thin film resistance layer 46 and a conductive layer 48 made of, for example, Cu are sequentially laminated on the entire surface.

Next, as shown in FIG. 9B, patterning is performed by integrally etching the conductive layer 48 and the thin film resistance layer 46 (see FIG. 4C).
Next, as shown in FIG. 9C, the uppermost Cu conductive layer 4 is formed.
The underlying thin-film resistance layer 46 is exposed on the surface by selectively pattern-etching only 8 (see FIGS. 4E and 4F). According to this, the thin film resistor can be formed at an arbitrary position by forming the via hole 44.

In the above embodiment, the case where the thin film resistor element is formed as the active element has been described. However, the present invention is not limited to this.
Alternatively, the coil element may be created using the method as described above. Here, a thin-film capacitor element manufactured using the above-described method will be described. Here, similarly to the above-described method of manufacturing a thin film resistor element, a thin film capacitor element is formed on a printed circuit board or is built in using a film forming technique (dry process) used in a semiconductor process or the like. I do. Specifically, the lower electrode layer, the dielectric layer, and the upper electrode layer are formed by a dry process such as sputtering (or a wet process such as plating). Other film formation methods using this dry process include:
Sputtering, ion plating, vapor deposition, CVD and the like can also be used. The feature of the film formation by the dry process is that the film thickness can be easily controlled, so that the film can be formed with a predetermined film thickness and with high accuracy, and the thin film can be easily formed to obtain a high capacity. Further, an accurate electrode pattern can be formed by a photolithography method.
As a result, a capacitor with small variation in capacitance and high accuracy can be obtained.

Here, a method for manufacturing the above-mentioned thin film capacitor element will be described with reference to the accompanying drawings. 10 and 11 are views showing a method of manufacturing the thin film capacitor element of the present invention, FIG. 12 is a perspective view showing the thin film capacitor element in FIG. 10 (G), and FIG. 13 is a plan view of the thin film capacitor element shown in FIG. FIG. First, in FIG. 10A, an insulating layer 14 is formed on a printed circuit board 12 similar to that described in FIG. 1 by screen printing or the like. This is the same as the structure shown in FIG. Note that FIG.
(B) to (G) and the printed circuit board 1 in FIG.
2 is omitted. Next, as shown in FIG. 10B, the insulating layer 14 is formed by a dry process such as reverse sputtering.
Surface is activated. At this time, this surface is not only activated at the molecular level, but is also roughened to some extent. At this time, the surface roughness Ra is 1 μm or less. next,
A material for the lower electrode layer 50 is formed by a dry process. The lower electrode layer 50 includes a contact layer 52 (for example, NiCr) and a conductive layer 54 (for example, Cu). Here, the thickness of the contact layer 52 is 0.1 μm,
The thickness of each of No. 4 was 0.3 μm, and each of them was formed sequentially by sputtering. The NiCr contact layer 52 is
It will also function as a thin film resistor described later.

Next, as shown in FIG. 10C, a metal mask (not shown) is set, and the lower contact layer 56 and the dielectric
8 and the upper contact layer 60 are sequentially formed and laminated by sputtering. Here, the lower and upper contact layers 56 and 60 are both made of NiCr, each of which has a thickness of 0.1 μm, the dielectric layer 58 is made of alumina, and has a thickness of 0.1 to 1.0 μm. It is.
Other materials for these contact layers include Pt, Ni,
Ti and the like. Other materials of the dielectric layer 58 include BST, PZT, STO, TiO ₂ and the like. Next, as shown in FIG. 10D, the metal mask is removed, and a material for the upper electrode layer 62 is sputtered to form a conductive layer 6.
4 is formed on the entire surface. Here, Cu was used as the material of the conductive layer 64, and the film thickness was 0.3 μm. Next, FIG.
As shown in (E), electric Cu plating is performed to form a Cu plating layer 66. Here, the thickness of the Cu plating layer 66 was 25 μm.

Next, as shown in FIG. 10F, a photoresist 68 is formed by a screen printing method or an electrodeposition method, and is patterned. At this time, the upper electrode layer 62
The area of the photoresist 68 corresponding to the area of the lower electrode layer is set to be slightly larger than the area of the lower dielectric layer 58, and the lower electrode lead-out pad 70 (FIG. 10).
A pattern of the photoresist 68 is also formed in a portion corresponding to (G). Next, as shown in FIG. 10G, the patterned photoresist 68 is used as a mask by an etching solution (a cupric chloride solution, a ferric chloride solution, or the like) generally used for a printed circuit board. ,
Perform pattern etching. Incidentally, copper or NiCr is etched as the etching solution, but the dielectric layer 58 is etched.
Use a material that cannot be etched. After that, the resist 68 is peeled off. The point in this step is that the upper electrode layer 62 and the lower electrode layer 50 are simultaneously etched and patterned to form no displacement between the upper and lower electrode layers 62 and 50. Thus, a thin film capacitor element 72 including the lower electrode layer 50, the dielectric layer 58, and the upper electrode layer 50 can be formed. in this case,
The lower electrode layer 50 extends further in the horizontal direction than the end of the dielectric layer 58, and the tip side is connected to a lower electrode lead-out pad 70, and the upper end of the pad 70 is connected to the upper electrode layer. The height is substantially the same as the upper end of the reference numeral 62.

FIG. 12 is a perspective view of only the thin film capacitor element 72 at this time, and FIG.
It is shown in FIG. In FIG. 10 (G), a land portion 7 for forming a thin film resistor element is described later.
4 is formed, and has a laminated structure of the contact layer 52, the conductive layer 54, the conductive layer 64, and the Cu plating layer 66. As described above, the thin film capacitor element 72 using the thin dielectric film can be formed on the insulating layer 14.
Further, when a thin-film resistor element is formed on the same insulating layer 14 as the insulating layer on which the capacitor element 72 is formed, the following steps can be added. To form this thin film resistor element, the land 74 shown in FIG. 10 (G) is used.

First, the insulating layer 1 having the structure shown in FIG.
As shown in FIG. 11A, a photoresist 76 is formed on the upper surface of the substrate 4 by a screen printing method or an electrodeposition method.
Patterning for forming a resistor element is performed. Next, FIG.
As shown in (B), only the Cu film is selectively etched with an alkaline etching solution (for example, A process manufactured by Meltex Co.) or a formic acid-based etching solution (for example, CZ8100 manufactured by MEC Co., Ltd.), and the contact of Ni—Cr is etched. A thin-film resistor element 78 composed of the layer 52 is formed. Next, the passive elements such as the thin film resistor element 78 and the thin film capacitor element 72 formed as described above are incorporated. First, Cu
After performing the surface treatment of the film, an insulating layer 80 is formed over the entire surface by screen printing or the like as shown in FIG.

Next, as shown in FIG. 11D, a VIA hole 82 for making contact by laser processing or the like is formed.
Is formed toward each electrode, and the surface of the insulating layer 80 is activated by a dry process such as reverse sputtering.
On this surface, a contact layer 84 (for example, NiCr) and a conductive layer 86 (for example, Cu) are sequentially laminated and formed. Here, the contact layer 84 has a thickness of 0.1 μm and the conductive layer 86 has a thickness of 0.1 μm.
Was set to 0.3 μm, and formed sequentially by sputtering. Next, as shown in FIG. 11E, electric Cu plating is performed on the entire surface of the printed circuit board to form a Cu plating layer 88. Here, the thickness of the plating layer 88 is 25
μm. Next, as shown in FIG. 11 (F), the contact layer 84, the conductive layer 86 and the Cu plating layer 88 on the insulating layer 80 are formed by the same method as described with reference to FIGS. 10 (F) and 10 (G). Perform patterning. As described above, the thin film capacitor element 72 and the thin film resistor element 78 can be built in the printed circuit board.

FIGS. 14 and 15 show the electrical characteristics of the thin film capacitor element 72 formed as described above. FIG. 14 is a graph showing the relationship between the thickness of the dielectric layer and the insulation resistance, and FIG. 15 is a graph showing the relationship between the thickness of the dielectric layer and the capacitance value. As is clear from the graphs shown in FIGS. 14 and 15, it was confirmed that as the thickness of the alumina as the dielectric layer 58 was larger, the insulation resistance was larger and the capacitance was smaller. Note that a desired capacitor capacitance value can be obtained by setting the area of the upper electrode layer 62 and the thickness of the dielectric layer 58. As described above, in the present embodiment, the thin film capacitor element can be formed on the insulating layer by a dry process used in a semiconductor process or the like. And the accuracy can be increased.

In addition, since the surface of the underlying insulating layer is activated by a dry process such as reverse sputtering to improve the adhesion with the upper layer, a conventional surface roughening method, which has a problem that frequent short circuits occur, is used. Unlike the above case, the withstand voltage can be improved, and the film can be thinned, which is advantageous for increasing the capacity. Since the upper electrode layer, the lower electrode layer (using the dielectric layer film as an etching mask) and the lower electrode lead-out pad are simultaneously subjected to pattern etching,
Thereby, the number of steps can be reduced. Also,
Since they are simultaneously pattern-etched, there is no shift in electrode position between the upper and lower sides. Further, since the upper electrode is formed by electroplating, the thickness of the upper electrode layer can be increased. As a result, the VI electrode can be formed directly above the thin film capacitor element without providing a lead-out pad for the upper electrode layer.
An A hole can be formed. Further, there is no damage to the upper electrode layer and the dielectric layer due to the surface treatment before the formation of the insulating layer. In addition, since the upper end of the upper electrode layer and the upper end of the lower electrode lead-out pad are substantially at the same horizontal level, the power of the processing laser can be set to be the same when forming a VIA hole, and there is no need to perform cumbersome power adjustment.

Further, the case where a thin-film resistor element or a thin-film capacitor element is formed as an active element has been described as an example, but the present invention is not limited to this. For example, a thin-film coil element can also be formed. In this case, FIG.
For example, as shown in FIGS. 16 and 17, a Cu plating layer 66, conductive layers 64 and 54, and a contact layer 52 may be spirally etched and formed on the ground portion 74 shown in FIG. Here, FIG.
0 is a plan view, and FIG. 17 is a sectional view taken along the line AA in FIG.

In the above embodiment, the dielectric layer 58 of the thin film capacitor element 72 is formed by sputtering, but it may be formed by paste printing or the like. Here, another modified example of the present invention formed as described above is shown in FIGS.
This will be described with reference to FIG. 18 and 19 are views showing a method for manufacturing a thin film capacitor element according to another modification of the present invention. Here, a case where a paste capacitor element is formed on one surface (upper surface) of a printed circuit board and a thin film resistor element is formed on another surface (lower surface) will be described as an example. Of course, it may be formed as follows. First, as shown in FIG. 18A, a conductive layer 92 made of, for example, Cu formed on the surface of the printed circuit board 12 is etched and formed in a predetermined pattern.
Further, this surface is micro-etched by using, for example, CZ-8100 manufactured by Mec Co., Ltd. in order to increase the adhesion strength. In the illustrated example, the conductive layer on the lower surface has been removed. As the conductive layer 92, a copper film formed in advance on the surface of the printed circuit board 12 or a copper film formed during lamination may be used.

Next, as shown in FIG. 18B, the entire surface of the printed circuit board 12 is coated with an organic resin having a low dielectric constant such as an epoxy resin to form an insulating layer 94. Next, as shown in FIG. 18C, a blind via hole 96 for forming a capacitor and a counterbore hole 98 for forming a capacitor are formed by using a CO ₂ laser or a YAG laser in order to establish conduction with the outer layer. An insulating layer 94 is formed corresponding to the conductive layer 92. In this case, when forming a recess having an area equivalent to a capacitor in the insulating layer 94 with a laser, the laser beam is moved at an interval of 1/2 to 1/1 of the diameter that can be opened in one shot, and the recess is formed by a pulse shot. Is good. According to this, the influence of the heat accumulated in the insulating layer 94 can be reduced, and a highly accurate area can be obtained.

Next, a paste containing a filler having a high dielectric constant such as barium titanate is printed with a squeegee 102 using a printing mask 99 corresponding to only the counterbore holes 98 as a mask to form a capacitor. The high-dielectric paste 100 is filled in the counterbore hole 98. The amount of the paste 100 to be filled at this time depends on the amount of the insulating layer 9 after curing.
The printing conditions such as the thickness of the print mask 99 are set to be equal to or slightly lower than the depth of the counterbore hole 98 of No. 4.
A dispenser may be used depending on the viscosity of the paste. Next, as shown in FIG. 18E, after the filled paste 100 is held until it is leveled flat, the paste 100 is cured. Next, as shown in FIG. 19A, the upper and lower surfaces of the insulating layer 94 and the surface of the paste 100 are activated (micro-etched) using plasma etching such as argon. The surface roughness Ra at this time is, for example, 0.01 to 1 μm.
m.

Next, as shown in FIG. 19B, nickel or a nickel alloy is thinly formed on the entire surface of both sides of the printed circuit board 12 by electroless plating or sputtering to form a contact layer 104. This contact layer 104
Is a resistance pattern on the lower surface side, and its thickness is adjusted according to a required resistance value. For example, the thickness can be adjusted within a range of 0.010 to 2.0 μm according to a required resistance value. Next, as shown in FIG.
A Cu plating layer 106 is formed on both surfaces of the printed circuit board 12 by electroplating using the contact layer 104 as a base.

Next, as shown in FIG. 19D, patterns for forming the outer layer conduction pattern, the resistor, and the capacitor are formed by using a dry film resist or an ED resist and an etching solution. As this etching solution,
An etching solution that dissolves both nickel or a nickel alloy and copper, for example, a cupric chloride solution or the like is used. In this case, the upper electrode layer 106 of the paste capacitor element 112
The size of A is preferably set at least one size larger than the diameter of the counterbore hole 18 at the bottom. According to this, the adhesion strength to the lower layer of the upper electrode layer 106A and the moisture resistance can be improved.

Next, as shown in FIG. 19 (E), a resist pattern is placed on the pattern serving as a resistor, and the lower surface is formed by using a selective etching solution that dissolves only copper without dissolving in nickel or a nickel alloy. By etching the side, a resistance pattern 108 is formed. Here, for example, a dry film resist is used, a formic acid-based CZ-8100 or an alkali developing type resist based on formic acid is used as an etchant, and an ammonia-based A process is used as an etchant (manufactured by Meltex Corporation).
Etc. can be used. Thereby, the thin film resistor element 110 on the lower surface side and the paste capacitor element 11 on the upper surface side
2 can be formed. Thereafter, solder resist for the soldering land, silk printing, and surface treatment (such as gold plating and heat-resistant flux) are performed as necessary.

In the present embodiment, the effect of providing a submicron anchor (irregularities) on the surface by plasma etching the surface of the paste 100 and the effect of activating the surface are utilized, and the bonding strength of the contact layer 104 is higher than that of copper. An electrode having high adhesion strength can be formed by using nickel or a nickel alloy having high strength and performing copper plating thereon. Also, when filling the high dielectric constant paste 100, the opening diameter of the print mask 99 is made smaller than the filling area, so that the high dielectric constant paste 100 does not protrude from the counterbore opening diameter, and the height of the paste is reduced by the insulating layer 94. By setting the thickness to be equal to or less than the thickness, a polishing step for removing the paste can be omitted, and the roughness of the surface of the insulating layer 94 can be suppressed by not polishing.

[0037]

As described above, according to the method for forming a thin film resistor element on a printed circuit board, the thin film resistor element and the thin film capacitor element of the present invention, the following excellent operational effects can be obtained. it can. According to the inventions defined in claims 1 to 3, it is possible to form a thin-film resistor whose dimensions and thickness are controlled with high precision. In contrast to the variation, the thin-film resistor of the present invention can suppress the variation to about ± 10% of the set value.
As a result, a high-precision thin-film resistor having good ohmic contact can be formed. According to the invention defined in claim 4, the heat generated from the thin-film resistor at the time of conduction can be efficiently radiated by the thin-film resistor or the structural design in the vicinity thereof. According to the inventions defined in claims 5 to 7, it is possible to form a thin film and upper and lower electrode layers and a dielectric layer with high planar dimensional accuracy, and consequently suppress variations in capacitance value and increase the thickness. It can be controlled with precision.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a thin film resistor element according to the present invention.

FIG. 2 is a perspective view showing a second embodiment of the thin-film resistor element according to the present invention.

FIG. 3 is a sectional view showing a third embodiment of the thin-film resistor element according to the present invention.

FIG. 4 is a process chart showing a method for manufacturing a thin-film resistor element.

FIG. 5 is an explanatory diagram illustrating a modified example of the present invention.

FIG. 6 is a cross-sectional view showing a thin-film resistor element having a heat-dissipating recess.

FIG. 7 is a cross-sectional view showing another thin-film resistor element having a concave portion for heat dissipation.

FIG. 8 is a sectional view showing still another thin-film resistor element having a heat-dissipating recess.

FIG. 9 is a sectional view showing a case where a thin film resistor is formed between inner layer circuit patterns.

FIG. 10 is a view showing a manufacturing method for manufacturing the thin film capacitor element of the present invention.

FIG. 11 is a view showing a manufacturing method for manufacturing the thin film capacitor element of the present invention.

FIG. 12 is a perspective view showing the thin film capacitor element in FIG. 10 (G).

FIG. 13 is a plan view of the thin film capacitor element shown in FIG.

FIG. 14 is a graph showing the relationship between the thickness of a dielectric layer and the insulation resistance.

FIG. 15 is a graph showing a relationship between a thickness of a dielectric layer and a capacitance value.

FIG. 16 is a plan view showing a thin-film coil element.

FIG. 17 is a sectional view taken along line AA in FIG. 16;

FIG. 18 is a view illustrating a method of manufacturing a thin-film capacitor element according to another modification of the present invention.

FIG. 19 is a view illustrating a method of manufacturing a thin-film capacitor element according to another modification of the present invention.

FIG. 20 is a process chart showing a conventional method for manufacturing a printed resistor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Thin film resistor element, 12 ... Printed circuit board, 14 ... Insulating layer, 16 ... Thin film resistor, 18 ... Conductive layer pad, 20 ...
Core material, 26 thin-film resistance layer, 28 conductive layer, 32 insulating layer, 34 concave portion for heat dissipation, 50 lower electrode layer, 58 dielectric layer, 62 upper electrode layer, 70 lower electrode lead-out Pad: 72: thin film capacitor element; 78: thin film resistor element; 110: thin film resistor element; 112: thin film (paste) capacitor element.

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) H05K 3/46 H05K 3/46 B (72) Inventor Mitsuru Otsuki 3-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Japan Victor Co., Ltd. (72) Inventor Shigeru Michiwaki 3-12-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Japan Victor Co., Ltd. (72) Koichi Kamiyama 3--12 Moriyacho, Kanagawa-ku, Yokohama-shi, Japan Japan Victor Co., Ltd. (72) Inventor Hisanori Yoshimizu 3-12-12 Moriyacho, Kanagawa-ku, Yokohama, Kanagawa

Claims (7)

[Claims] 1. A method for forming a thin film resistor element on a printed circuit board, wherein the thin film resistor layer having a predetermined thickness is formed on an insulating layer on the printed circuit board by a dry process used in a semiconductor process or the like. A forming step, a conductive layer forming step of forming a conductive layer on the thin-film resistance layer, and selectively etching the conductive layer to form at least two conductive layer pads, thereby providing a predetermined space between the conductive layer pads. A step of forming a thin film resistor having a resistance value of: 3. A method of forming a resistor element on a printed circuit board. 2. The method according to claim 1, wherein the thin film resistor is formed at the time of forming a build-up substrate or a build-up multilayer substrate in which an insulating layer and a patterned conductive layer are sequentially laminated on a core material. A method for forming the resistor element according to the above. 3. A thin film resistor element on a printed circuit board, comprising: a thin film resistor layer having a predetermined thickness formed on a dielectric layer on the printed circuit board by a dry process used in a semiconductor process or the like; And at least two conductive layer pads formed apart from each other on the thin film resistance layer to form a thin film resistance element. 4. In the case where the thin-film resistor is a thin-film resistor provided in an inner layer, a heat-dissipating recess is formed in an upper portion of the thin-film resistor or in an insulating layer above a conductive layer in the vicinity thereof. 4. The thin film resistor element according to claim 3, wherein said thin film resistor element is formed. 5. A thin film capacitor element on a printed circuit board, comprising: a lower electrode layer having a predetermined thickness formed on an insulating layer on the printed circuit board by a dry process used in a semiconductor process or the like; A dielectric layer formed by the dry process, and an upper electrode layer formed by the dry process on the dielectric layer, wherein the lower electrode layer extends more horizontally than the upper electrode layer A thin-film capacitor element on a printed circuit board, wherein the thin-film capacitor element is connected to a lower electrode lead-out pad. 6. The thin-film capacitor element according to claim 5, wherein an upper surface of the upper electrode layer and an upper surface of the lower electrode lead-out pad are substantially at the same height. 7. The insulating layer on the printed circuit board is the same as the insulating layer on which the thin-film resistor element defined in claim 3 is formed, and is provided on the same surface as the thin-film resistor element. 7. The thin film capacitor element on a printed circuit board according to claim 5, wherein